Motor-control system



March 27, 1928. w 1,664,216

H. D. JAMES MOTOR CONTROL SYSTEM Filed Sept. 2. 1922 WITNESSES: INVENTOR W Henry D. Jamaa- Patented Mar. 27, 1928.

UNITED STATES PATENT OFFICE.

HENRY 1). JAMES, 0F EDGEWOOD PARK,

HOUSE ELECTRIC & MANUFACTURING VANIA.

MOTOR-CONTROL SYSTEM.

Application filed September 2, 1922. Serial No. 585,850.

My invention relates to systems of distribution and it has particular relation to motor control and the protection of switching apparatus employed in such systems.

The object of my invention is to provide means for preventing the opening of circuit-controlling devices while excessively heavy current is traversing the circuit.

It is customary to employ a knife switch in the mainline circuit of a motor, together with a 1'emotely-controiled s :ch contactor type for starting and stop) motor. The main circuit may be int rupted by opening the knife switch bu under certain load conditions, this operation is very undesirable on account of danger to the operator and probable destruction of the switch.

In one form of my invention, I employ a latching mechanism that controlled by the main current, for preventing the open-- ing of the knife switch while the load current traverses the main circuit.

My invention will be described in connection with the accompanying drawing, in which the single figure is a diagrammatic representation of circuits and apparatus enibodying my invention.

Referring to the drawing, a motor, des nated generally as 1, is connected through a knife switch 2 and a contactor 3 to line conductors 4 and The knife switch 2 is provided with a latching mechanism comprising a latch G, a coil 7 and armature 8. A spring 9 normally maintains the armature 8 and hence,

the latching mechanism in unlocked position. The armature 8 is pivotally mounted on an intermediate bearing.

A control switch 11 is arranged to complete a circuit for the operating coil of the contactor 3. \Vhen the switches 2 and 11 and the contactor 3 are closed, a circuit is completed from line conductor l through coil 7, knife switch 2, motor 1 and contactor 3 to line conductor 5. The armature S is attracted to its closed or illustrated position, thereby latching the knife switch, when the latter occupies its closed position, and preventing the opening thereof until the motor current has been reduced to a predetermined low value.

The motor 1 is controlled by means of the switch 11, which is located, as is customary,

at any convenient point, while the latching device eliminates the danger of opening the switch 2, as is sometimes done in an emergency, or inadvertently, prior to the opening of contactor Although I have illustrated my invention in preferred forms, various modifications may be made in details and general arrangementwithout departing from the spirit and scope of my invention, and I desire, there fore, to be limited only by the scope of the appended claims.

I claim my invention:

1. The combination with a motor and a. circuit interrupting switch therefor, of an additional switch for interrupting the motor circuit and means comprising a series coil for preventing the operation of said additional switch prior to the operation of the first switch.

2. The combination with an electric circuit and a remotely controlled circuit-in terruptor therefor, of a manually operable switch for also controlling said circuit means for latching said switch in its closed position and a coil responsive to load conditions of said circuit for rendering said latching means effective to prevent opening said switch prior to operation of said circuit interrupter.

The combination with a translating device and a controlling device therefor having an operating coil connected in parallelcircuit relation to said translating device, of a second controlling device having a coil connected in series-circuit relation with said translating device and being effective to prevent the o eration of said second controlling device to interrupt the flow of current through said translating device.

4. The combination with a translating de vice and a switch connected in circuit therewith, of a latch, means for normally biasing said latch to a position permitting the opening of said switch, and a coil connected in series-circuit relation with said translating device for operating said latch to a position to prevent the opening of said switch while current is flowing theret-hrough.

In testimony whereof, I have hereunto subscribed my name this 30th day of August, 1922.

HENRY D. JAMES. 

